As elsewhere, the process is random.
This group of parameters can be used to specify how the selected part of the Image Source will (or will not) be transformed to fill the element.

Flip Horizontal - flips the content of the element horizontally.
Flip Vertical - similarly vertically.
Rotate 180° - Rotate the content of the element 180 degrees.
Rotate 90° CW - Randomly rotate the content of the element 90 degrees clockwise. Active only when there is a square element in the pattern.
Rotate 90° CCW - Randomly rotate the contents of the element 90 degrees counterclockwise. Active only when there is a square element in the pattern.